Vlassi M, Steif C, Weber P, Tsernoglou D, Wilson K S, Hinz H J, Kokkinidis M
University of Crete, Dept. of Biology, Heraklion, Greece.
Nat Struct Biol. 1994 Oct;1(10):706-16. doi: 10.1038/nsb1094-706.
The sequences of alpha-helical coiled-coils and bundles are characterized by a specific pattern of hydrophobic and hydrophilic residues which is repeated every seven residues. Highly conserved breaks in this pattern frequently occur in segments of otherwise continuous heptad substructures. The hairpin bend of the ROP protein coincides with such a break and provides a model system for the study of the structural effects induced by heptad discontinuities. The structure of a ROP mutant which re-establishes a continuous heptad pattern, shows insignificant changes relative to the wild-type protein, as is also reflected in its conformational stability, spectroscopic properties and unfolding behaviour. Thus, formation of alpha-alpha-hairpin bends may occur both in the presence and absence of heptad breaks.
α-螺旋卷曲螺旋和束的序列具有特定的疏水和亲水残基模式，该模式每七个残基重复一次。在其他方面连续的七肽亚结构片段中，这种模式经常出现高度保守的断裂。ROP蛋白的发夹弯与此类断裂重合，并为研究七肽不连续性诱导的结构效应提供了一个模型系统。重新建立连续七肽模式的ROP突变体的结构，相对于野生型蛋白显示出微不足道的变化，这也反映在其构象稳定性、光谱性质和去折叠行为上。因此，无论是否存在七肽断裂，α-α发夹弯都可能形成。
